This proposal requests NIH funding for purchase of equipment for a combined x-ray fluoroscopy/3.0T MRI (XMR) suite in the Department of Radiology and Biomedical Imaging at the University of California San Francisco (UCSF.) The equipment will be sited in an in-patient location at UCSF, replacing an existing XMR suite that provides the only research-dedicated imaging resource for in-patient studies at UCSF. This suite will provide the capabilities urgently needed to continue and extend a broad range of ongoing research projects that all promote the goal of clinically-relevant, image-guided interventional treatments. The proposal is part of a partnership between researchers and the Medical Center at UCSF and thus falls under the classification of a Special Use Instrument (SUI). The cost and the use of the equipment will be equally shared between research and clinical use. Previous experience at UCSF indicates that in order to effectively frame and pursue image-guided interventions, this shared mode imposes the constraints on research developments that result in viable capabilities that can be readily translated into clinical practie. This suite will be used by investigative teams from a broad range of diagnostic and surgical specialties with a strong track-record of collaboration. The equipment will directly benefit a number of NIH-funded projects, and will, importantly, provide a powerful resource for several junior investigators who have nascent programs in related areas. The equipment provided through this funding mechanism will enable the continuation of a substantial effort at UCSF that has been pursued with NIH-funding on an existing XMR suite that was installed in 2001, is now obsolete, and will no longer be supported by the vendor beyond March 2016. Current plans for the suite are for the Medical Center to replace the equipment. It would therefore no longer be available for research studies. The specific programs that would be enabled by funding from an HEI-S10 award include: Monitoring the distribution of therapeutics as they are injected into different target areas (e.g., brain tumors or atherosclerotic lesions of the peripheral vessels); Monitoring laser-delivered, thermal ablation treatments; Evaluation of the response of aneurysmal disease to stenting; Guiding endovascular approaches using mechanical devices for clot retrieval in stroke treatment; Assessing the efficacy of ablations for treating arrhythmia; Guiding endovascular cell sampling; and, Determining the hemodynamic impact of vascular interventions. These studies will provide new insights into the physiological effectiveness of different treatment strategies, will provide novel therapeutic delivery approaches that are potentially more effective, and have lower associated risks, than conventional methods, and will develop practical translational strategies that can be readily transferred to clinical practice.